My meteorites: Sikhote-Alin shrapnel (186g)

April 30, 2018

This is one of my favorite things: a piece of shrapnel from the Sikhote-Alin meteor that exploded over Russia on February 12, 1947. I picked it up at RTMC a couple of years ago.

I love it because it looks exactly like what it is: a wrecked piece of iron, fractured with the rest of its parent body from the core of long-destroyed planetoid, blasted asunder in the atmosphere in a multi-kiloton airburst, and finally shattered against the bedrock of the Sikhote-Alin mountains in far eastern Siberia. Every surface bears witness to the awesome energies of its birth, unleashed in a chain of events that we can barely comprehend, and certainly could not survive.

It fits perfectly in the hand, inviting you to run your thumb over its cracks, pits, and twisted, jagged edges. It has a satisfying heft, befitting a solid chunk of metal. It is 93% iron and 6% nickel, with small amounts of cobalt, phosphorus, and sulfur, and bare hints of germanium, gallium, and iridium. At room temperature it feels cold to the touch, as if it somehow still holds the chill of space.

I like to pass it around and have people handle it. With its weight, seemingly unnatural coolth, and textures that so clearly tell the story of its creation, it’s a fantastic hand specimen. I like to hold it myself, and think about the billions of years it spent in space. It was floating around out there while our ancestors attained multicellularity, backbones, limbs, amniotic sacs, hair, bipedality, fire, agriculture, writing, telescopes, powered flight, and the ability to split the atom. And then our paths crossed, quite literally, when the trajectory of the Sikhote-Alin meteoroid intersected that of Earth.

The energy released by the airburst of the Sikhote-Alin meteor is estimated at 10 kilotons (for comparison, the Chelyabinsk meteor in 2013 was about 500 kilotons). In all the long history of Earth, such large explosions had been the exclusive province of volcanoes and asteroid and comet strikes. But the Sikhote-Alin meteor entered a new world, where its 10-kiloton detonation was only the sixth largest explosion on Earth in the preceding 20 months, behind the atomic blasts at Trinity, Hiroshima, and Nagasaki in 1945, and the Able and Baker tests at Bikini Atoll in 1946 (all between 16 and 23 kilotons).

It is hard to think about such things, so removed from us in time, and from the scale of our experiences. I hold this cold piece of sharp-edged iron and think about all of the other Sikhote-Alins, Chelyabinsks, Tunguskas, and Chicxulubs out there, any of which might cross our path at any moment, and some of which inevitably will. In the words of the astronomer Kevin Zahnle (quoted in Seeing in the Dark by Timothy Ferris), “a day will surely come when the sheltering sky is torn apart with a power that beggars the imagination.”

Because it is only a matter of time until Earth is threatened with a civilization-ending or mass-extinction-level impact, is is also only a matter of time until we stop thinking of astronomy as the niche preoccupation of a few, and start realizing that it is an unavoidable aspect of our survival.

We need reminders of that fact. This one is mine.



  1. Very interesting sample and essay.

  2. Thank you! I should have mentioned in the post that Sikhote-Alin meteorites come in two flavors: individuals, which separated in the atmosphere and were individually ablated on the way down, becoming marked with flow lines and regmaglypts (“thumbprints”); and shrapnel, like the piece shown here, which were parts of larger individuals that shattered when they hit the ground. The shrapnel can be pretty darned big – there is a piece of Sikhote-Alin shrapnel the size of a dinner plate at the Arizona Museum of Natural History. Individuals fetch higher prices, but I prefer the shrapnel – nice Sikhote-Alin individuals don’t look that different from the atmosphere-sculpted individuals of any other meteorite fall (although they are often recognizable based on color and texture), whereas the shrapnel doesn’t really look like anything else (that I personally have seen, anyway). It’s waaay different from the Campo del Cielo pieces, like the one I showed in the last installment in this series.

  3. […] slowly going through my (small) meteorite collection over at 10 Minute Astronomy. I just covered my Sikhote-Alin chunk, in what I immodestly think is one of my better posts. Go see if you […]

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